Process for the production of saturated ketones



. UNIT Patented Jan. 9,1945

so STATE ass'zms Paocass Foa THE PRODUCTION OF SATURATED n'romss CharlesWeizmann, New York, N. Y,

. No Drawing. Application July '1, 1943,

. Serial No. 493,705

' 2 Claims.

This invention relates to improvements in processes for the productionof saturated ketones from a, p-unsaturated ketones, and particularly forthe selective hydrogenation, of the carboncarbon-double bond in a,p-unsaturated ketones, 5

the main object of the invention being to provide a practical-andeffective m unsaturated ketones to form saturated ketones,

Many interesting been found for satu applications have recently ratedhigher molecular ketones, such for example as starting materials forchemical syntheses and as components of highoctane fuel because tanenumber.

The production of spending a, not easy as of their unusually high ocsuchketones from the correfl-unsaturated ketones is, however, it isnot-always simple to stop the reaction after hydrogenation of thecarbon-car hon-double bond only, without affecting the carbonyl group.Such a, pig-unsaturated ketones are known to be easily available bycondensation of aldehydes with ketones or by self condensation ofketones as for ex pending applications ample, described in my co- SerialNos. 464,788 and 464,-

789, of which the present application is a continuation in part. I havenowiound that the unsaturated ketones thus 0 btained may advantageouslybe reduced to form saturated ketones by means of hydrogen, using ascatalyst Raney nickel and carrying out 'the hydrogenation under neutralor acid conditions. In a slightly acidic medium, the

rate of hydrogen absorptiondecreasespractically' to zero, when the C=Cdouble bond -is saturated, and no attack on the-carbonyl group is to befeared. The acidity of the medium can be created by addition or smallamounts or organic acids, or preferably by addition of hydrohalides oftertiary amines. the reaction can be a According to the inventiondvanta'geously carried out at ordinary temperature and presure thoughin.- creased pressure and temperature may be used if desired.- In manycases no diluent is required,

andin some cases only a small quantity or diluent is used.

ethod of reducing the manner in which the invention may be carried out,but it is to be understood that the invention is by no means limited tothe details given therein:

Example I .-98 grams of mesityl oxide were hydrogenated after additionof 2 cubic centimeters glacial acetic acid, under ordinary pressure andat room temperature, in the presence of 1 gram of freshly prepared Raneynickel. The absorption of the theoretical quantity of hydrogen lastedtwo hours. The supernatant liquid was neutralized with solid sodiumcarbonate and distilled. A theoretical yield of methyl-isobutyl-ketone,boiling point 116 C. was obtained.

Example IL- Hydrcgen is passed into a mixture of 126 grams of3.4-dimethyl-3- hexane-2- one with 0.5. gram trimethylaminehydrochloride and 50 grams of alcohol in the presence of 2 grams ofRaney nickel. After the absorption of ,1 molecule of hydrogen, thereaction came to a standstill. The filtered solution was distilled in avery eflicient column as the saturated ketone tends to distill withalcohol vapours. The product obtained in quantitative yield is3.4-dimethyl-2- hexanone, boiling point 158-159.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:'

of the carbcn-carbon-double bond in a, p-unsaturated ketones, whichconsists in carrynig out the reaction in the presence of Raney nickel ascat- 1. The process for the selective hydrogenation alyst in a medium ofwhich the pH value is maintained slightly on the acid side by adding tothe '40 reaction mixturea' salt which is a member of the groupconsisting of the hydrochlorides and hydrobror'nides or tertiary amines,dissolved in a small'quantity of an alcohol.

- CHARLES @WEIZMANN.

